Explain the metaphor beyond the symbol by choosing the phrase that establishes what is similar in the pair of words. Select the item that best expresses this. Use your notes if you need them. life: sea.
Life is to sea.
It is said that all life has come from the sea and this does seem to make sense. After all after the big bang and after earth got an atmosphere land rose out of the ocean and soon some ocean lifeforms adapted to live on land, no longer confined to the water.
The explanation is that life came from the sea and thus they are related.
Of course the other relation is that there is a lot of sea life our there, most likely more than even the land. So you could use that too.